Context
High serum or dietary levels of vitamin E and beta carotene
appear to be associated with lower risk of stroke, but studies regarding
their supplementation have not supported their use in stroke
prevention.
Objective
To determine if vitamin E (dl-alpha tocopherol) and
beta carotene supplementations could be used in prevention of stroke in
men at high risk for hemorrhagic or ischemic events.
Design
Population-based, randomized, double-blind,
placebo-controlled, 2 × 2 factorial design trial (the Alpha-Tocopherol,
Beta-Carotene Cancer Prevention Study), conducted from April 1985
through April 30, 1993, with median follow-up of 6 years.
Interventions
Alpha tocopherol, 50 mg; beta carotene, 20 mg; both; or placebo.
Participants
From the total male population aged 50 through 69 years in
southwestern Finland (n = 290,406), 29,133 male smokers were randomized
to 1 of 4 treatment regimens. We excluded 614 men because of previous
stroke at baseline, leaving 28,519.
Main Outcome Measures
Incident and fatal subarachnoid and intracerebral hemorrhage, cerebral infarction, and unspecified stroke.
Results
Stroke occurred in a total of 1057 men: 85 had subarachnoid
and 112 had intracerebral hemorrhage, 807 had cerebral infarction, and
53 had unspecified stroke. Within 90 days from onset, 160 men died of
stroke. Vitamin E supplementation increased the risk of subarachnoid
hemorrhage (relative risk [RR], 2.45; 95% confidence interval [CI],
1.08-5.55) and decreased risk of cerebral infarction (RR, 0.70; 95% CI,
0.55-0.89) in hypertensive men but had no effect among normotensive men.
Furthermore, it decreased the risk of cerebral infarction, without
elevating the risk of subarachnoid hemorrhage, among hypertensive men
with concurrent diabetes (RR, 0.33; 95% CI, 0.14-0.78). Beta carotene
supplementation appeared to increase the risk of intracerebral
hemorrhage and modestly decrease that of cerebral infarction among men
with greater alcohol consumption.
Conclusion
Vitamin E supplementation may prevent ischemic stroke in high-risk hypertensive patients, but further studies are needed.
VITAMIN E and beta carotene may act as antioxidants against atherosclerosis and thus prevent cerebrovascular diseases.1,2 Besides the antioxidant effects, vitamin E and its metabolites have antiplatelet and anticlotting actions,3-6
but the clinical importance of these actions is obscure. In our
controlled trial on male smokers, the Alpha-Tocopherol, Beta-Carotene
Cancer Prevention (ATBC) Study, vitamin E (dl-alpha tocopherol)
supplementation increased the incidence and mortality due to
subarachnoid hemorrhage but decreased the incidence of cerebral
infarction, whereas beta carotene supplementation increased the
incidence of intracerebral hemorrhage.7
Our aim was to examine whether there were subgroups that
benefited from supplementation with vitamin E or beta carotene without
an increased risk for bleeding. For this, we analyzed the effect
modification of age, systolic blood pressure, serum total and
high-density lipoprotein (HDL) cholesterol levels, histories of diabetes
and heart disease, number of cigarettes smoked daily, alcohol
consumption, and physical activity on the effects of vitamin E
supplementation on subarachnoid hemorrhage and cerebral infarction, and
that of beta carotene supplementation on intracerebral hemorrhage and
cerebral infarction in the ATBC Study.
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